Certain substituted-heteroaryl herbicides are described in PCT publication Nos. WO 95/29898 and 95/29893 which are incorporated herein by reference.
One preferred class of these herbicides are substituted-pyrimidines which have the following structure: ##STR1## wherein Q is trifluoromethyl, fluoro, chloro, bromo, iodo, methoxy, methyl, or ethyl; q is 0,1,2,3,4or5;and
R is of the formula ##STR2## wherein R.sup.6 is C.sub.1 -C.sub.6 alkyl or is of the formula N(R.sup.7)(R.sup.8), wherein R.sup.7 and R.sup.8 are independently hydrogen, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 alkyl, C.sub.2 -C.sub.6 alkenyl or together R.sup.7 and R.sup.8 form a pyrrolidine ring.
Y is halogen, C.sub.2 -C.sub.6 alkenyl, C.sub.2 -C.sub.6 alkynyl, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 haloalkyl, C.sub.1 -C.sub.6 alkoxy, C.sub.1 -C.sub.6 haloalkoxy, nitro, cyano, C.sub.1 -C.sub.6 alkylcarbamylthio, mercapto, hydroxy, thiocyano, (C.sub.1 -C.sub.6)-alkoxy-(C.sub.1 -C.sub.6)alkyl, --S(O).sub.k --R.sup.10 or --N(R.sup.11)(R.sup.12) wherein k is 0, 1 or 2;
R.sup.10 is C.sub.1 -C.sub.6 alkyl or phenyl;
R.sup.11 and R.sup.12 are independently C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkylthio or C.sub.1 -C.sub.6 alkoxy; n and m are independently 0 or 1 and p is 0, 1, 2, or 3.
As is discussed PCT publication WO 95/29898, compounds of formula I may be made using the following general procedure. First, a benzoyl chloride is reacted with the magnesium enolate of an appropriate .beta.-ketoester to form a triketo intermediate followed by hydrolysis and decarboxylation to a .beta.-diketone intermediate. The diketone is then converted to the alkoxy methylene or dialkylaminomethylene .beta.-diketone by standard methods. Final ring closure to the pyrimidine is accomplished by heating with formamidine acetate in an alcoholic solvent, followed by reduction of the resulting benzoyl pyrimidine, to produce a hydroxybenzyl pyrimidine compound.
Using the above procedure, the decarboxylation reaction to generate the .beta.-diketone intermediate produces an unwanted by-product, namely an aryl methyl ketone. Surprisingly, the inventors have discovered that if the .beta.-keto ester contains an allyl group or a substituted allyl group, the decarboxylation reaction to generate the aryl-.beta.-diketone proceeds without the generation of an aryl methyl ketone. The fact that no aryl methyl ketone is generated greatly reduces the costs of production.